feat(12.1-01): declared bulk actions on admin lists

- pact.HasAdminBulkActions with AdminBulkAction, its input and result
- config_list.yaml bulkActions, compiled fail-loud, needs showCheckboxes
- POST .../{controller}/bulk/{action}: ids resolved and locked through the
  list scope in one transaction; partial selection is 409
- list schema offers declared actions per principal, with confirm text
- admin SPA bulk actions menu with confirm, busy state and failure toasts
- acme.roster fixture, tracer test, OpenAPI, TS types, dist, READMEs, docs

admin/tests/fixtures/roster.list.json

@@ -0,0 +1,8 @@
+{
+  "data": [
+    { "id": 1, "name": "Ada Lovelace", "email": "ada@example.test" },
+    { "id": 2, "name": "Bob Stone", "email": "bob@example.test" },
+    { "id": 3, "name": "Cy Young", "email": "cy@example.test" }
+  ],
+  "meta": { "page": 1, "per_page": 20, "total": 3, "last_page": 1 }
+}